Bus On Shoulder System (BOSS)

The bus on shoulder system in the Research Triangle region – a cooperative initiative of Triangle Transit and NCDOT, in concert with other partners – is the largest by system mileage in the southeast and the second largest in the United States after Minnesota’s Twin Cities.

Bus on shoulder service is a low cost, inherently low speed, peak operational treatment that can provide immediate benefits to transit whenever mainline travel is experiencing moderate to heavy degrees of congestion. Bus on shoulder operation allows authorized transit buses with trained drivers to operate on the shoulders of selected freeways and other highways in order to bypass congestion and maintain transit schedules, subordinate to the primary use of the shoulder for emergency purposes, and subject to maximum speed and speed differential thresholds.

Buses can only use shoulders when travel speeds are below 35 MPH in the main lanes, and buses can only travel up to 35 MPH in the shoulder — and they are limited to no more than 15 MPH faster than other vehicles. In addition, bus on shoulder operation is a subservient use of the shoulder: the primary use of the shoulder as a breakdown lane for emergency operations continues as normal, and buses must yield to everything in the shoulder.

Bus on shoulder operations were first implemented in Minnesota more than 20 years ago, with more than 300 shoulder-miles in use today in the Minneapolis-St. Paul region. More than 60 shoulder-miles of freeway in the Research Triangle region currently have bus on shoulder service available for regional transit use.